The use of radiation to treat medical conditions comprises a known area of prior art endeavor. For example, radiation therapy comprises an important component of many treatment plans for reducing or eliminating unwanted tumors. Unfortunately, applied radiation does not discriminate between unwanted materials and adjacent tissues, organs, or the like that are desired or even critical to continued survival of the patient. As a result, radiation is ordinarily applied in a carefully administered manner to at least attempt to restrict the radiation to a given target volume.
Jaws and multi-leaf collimators are often used to restrict and form the radiation-therapy beam. Both components are typically made of high atomic numbered materials (such as tungsten) to form an effective radiation block. Jaws typically comprise two blocks that are selectively moved towards or away from one another to control the size of the gap between these two blocks. Jaws are usually either vertically oriented (in that the blocks move vertically) or horizontally oriented (in that the blocks move horizontally).
Multi-leaf collimators are comprised of a plurality of individual parts (known as “leaves”) that can move independently in and out of the path of the radiation-therapy beam in order to selectively block (and hence shape) the beam. Some modern multi-leaf collimators include upwards of one hundred such leaves that can be individually moved in order to form a corresponding beam-shaping aperture. These leaves are typically used to specifically shape the radiation-therapy beam. By way of contrast, jaws are typically used to form a general frame or outer boundary around the multi-leaf collimator's beam-shaping aperture to thereby reduce leakage through the multi-leaf collimator.
Some treatment plans provide for adjusting the multi-leaf collimator to accommodate various differences that occur or accrue when, for example, moving the radiation source with respect to the target volume during a given radiation-treatment session. Though a powerful and flexible capability, unfortunately, such use of multi-leaf collimators during treatment is not wholly satisfactory for all application settings.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.